The disclosure relates to a drive apparatus mounted in a hybrid vehicle, which runs using both an engine and a motor, and a control method and control device therefor.
Art related to a control during engine starting in a drive apparatus mounted in a hybrid vehicle, the hybrid vehicle driven by both an engine and a motor, can be found, for example, in U.S. Pat. No. 6,581,705 (Cols. 1-6, FIGS. 1, 2A and 2B) of the family of Japanese Patent Laid-Open Publication No. 2003-129926 (pages 1-5, FIGS. 1, 2A and 2B) described below. The reference describes control for a parallel hybrid vehicle with an engine disconnect clutch. The purpose of the control is to engage the engine disconnect clutch and start the engine, while also maintaining a smooth vehicle response to a driver request using the motor. In this case, the motor is controlled throughout engine starting in a speed following control mode, which performs a control adapted to the torque required to obtain a desired setting speed. In other words, during engine starting, the engine disconnect clutch is first engaged and then the desired speed is issued to the motor, after which fuel is supplied to the engine to start the engine. Because the motor is controlled in the speed following control mode at this time, the output torque of the motor is controlled so as to maintain the desired speed, regardless of whatever magnitude of torque is required for starting the engine.
The reason such a control is performed in the speed following control mode is because no matter how much the torque required for engine starting fluctuates, the vehicle speed can be maintained at a predetermined speed and a smooth vehicle running condition can be maintained using a simple control in the speed following control mode.
Following engine start, a control is performed that calculates the desired engine torque, and then gradually decreases the motor torque while increasing the engine torque a proportional amount. This continues until the motor torque reaches zero. The vehicle speed is maintained throughout using, for example, a proportional/integral controller. In this case, the desired motor speed is set based upon a request from the driver and the overall vehicle operating condition. Either a trajectory or constant value therefor may be obtained based upon the acceleration and the vehicle speed at the present time and at a past point in time.